Ethylene acrylic acid (EAA) copolymers and maleic anhydride (MAH) modified polymers are known to adhere well with polar materials. However, adhesive films prepared with high amounts of EAA copolymers or MAH polymers tend to be too expensive for routine use in many applications, such as in the production of automotive parts like headliners. In an attempt to provide lower cost adhesive films that exhibit good adhesive properties with polar materials, others have blended polymers exhibiting good adhesion to polar materials with less expensive olefin polymers. However, these blends still tend to be too expensive for many applications, or to exhibit unacceptable adhesion to polar materials or both.
It is also known to incorporate a catalytic amount of an acidic agent or a basic agent into an adhesive composition that contains a grafted polyolefin in order to enhance adhesion. The catalytic agent is selected from monoalkyl phosphates, dialkyl phosphates, monoalkylamines, dialkylamines, trialkylamines, heterocyclic amino compounds, aminocarboxylic acids and salts of such acids. Examples of amines include tributylamine and trioctylamine. A disadvantage in using these amines, both of relatively low molecular weight, as catalytic agents is that they tend to volatilize, especially at temperatures needed to melt blend the catalytic agents with EAA copolymers, MAH-modified polymers or both. Volatilization of the amine catalytic agents may present health, safety and environmental issues, all of which are desirably avoided.
It is also known in the art to react primary amino- or hydrazide-substituted ultraviolet (UV) absorbers with some or all of the anhydride groups of anhydride containing polymers or copolymers to form pendant stabilizer substituted iinide or amic acid groups. An amic acid results from a reaction between an anhydride and an amine wherein the amine attacks one anhydride carbonyl group to produce an amide while leaving a second carbonyl group unreacted as a carboxylic acid. The resulting polymeric stabilizers may be used as is or as concentrates to stabilize other polymer systems. Polymeric or polymer bound stabilizers are not lost from a polymer system by volatilization, migration, or extraction, even at high temperatures. Although the polymeric stabilizers themselves are not subject to volatilization, they are prepared from a primary amino-substituted 2-hydroxybenzophenone, a primary amino-substituted salicylic acid ester or primary amino-substituted oxalic acid amide, all of which are low molecular weight molecules that could volatilize when melt blended with anhydride-containing polymers or copolymers. The polymeric stabilizers prepared by reacting primary amino compounds with anhydride containing polymers or copolymers are not known to be used as adhesives or adhesion promoters.